Method and apparatus for arterial and venous blood sampling

ABSTRACT

A method and apparatus for arterial and venous blood sampling. The apparatus includes an efficient means of purging the fluid line and a fluid sampling device chamber of residue heparin solution to obtain and return a sufficiently undiluted blood sample without excessive blood waste and risk of entry of air, line contamination/nosocomial infection or misdiagnosis. The apparatus is also specially designed to protect the clinician from either self-contamination from patient fluids, accidental injection of medication or accidental injury from needle puncture.

This is a Continuation-In-Part of Copending Continuation-In-PartApplication, Ser. No. 07/208,388 filed June 17, 1988, now U.S. Pat. #4,920,970 which is a Continuation-In-Part of Ser. No. 06/907,118 filedSept. 12, 1986 now U.S. Pat. # 4,763,648.

BACKGROUND OF THE INVENTION

The present invention concerns an improved method and apparatus forproviding sterile access to fluid lines for fluid sampling. Moreparticularly, the invention relates to an improved method of obtainingprecise volumes of substantially undiluted samples of arterial or venousblood for use in blood gas analysis and related therapeutic techniques.

2. Discussion of The Prior Art:

Arterial blood pressure measurements have been investigated for morethan 250 years. Over the years, the techniques of direct pressuremonitoring have been modified and improved so that they now provideclinicians with a valuable tool useful for many purposes, including thedirect method of obtaining laboratory specimens of arterial/venous bloodfrom intravenous and/or pressure monitoring lines which areinterconnected invasively to the patient.

Within about the last ten years, equipment for direct pressuremonitoring has become easier to use, more functional and more readilyavailable. The increase utilization of indwelling arterial/venouscatheters has allowed clinicians to take advantage of the easy access tothe intra-arterial/venous lines for blood sampling. Accordingly, presentpractice is to draw substantially all blood specimens from theintra-arterial/venous lines when they are used, thereby decreasing thenumber of venipunctures required.

Several products and procedures presently exist for use in drawingfluids from arterial/venous monitoring systems. One current method usesan idle sideport of a three port stopcock which is protected by anonvented port protector for sterility and is attached to tubing in atypical pressure monitoring system. Other methods involve the use of avariety of types of commercially available "T-connectors" or "heparinlock" injection/aspiration sites which may be attached at the sideportof a three port stopcock disposed within the most frequently used typesof pressure monitoring systems or in-line between the arterial/venouscatheter and the pressure monitoring line. These prior art samplingsystems and procedures as well as the numerous drawbacks thereof will bediscussed in greater detail in the paragraphs which follow.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method and apparatusthat will effectively eliminate the clinical problems now associatedwith arterial and venous blood sampling. More particularly, it is anobject of the invention to eliminate problems such as air entry and linecontamination associated with the opening of closed monitoring systems,sample dilution and excessive blood waste, the potential for bleedoutand the inability to effectively purge lines of either air, heparinizedsolution or residue blood.

Another object of the invention is to provide a novel sampling apparatuswhich is easy to use and effectively prevents accidental skin needlepuncture, thereby protecting the clinicians from dangerous and sometimesfatal infection.

Still another object of the invention is to provide a method andapparatus of the aforementioned character which is safe, reliable,highly cost effective and serves to minimize the need for componentreplacement, clinician resampling time and prolonged patienthospitalization due either to nosocomial infections or inaccuratetherapeutic treatment caused by misdiagnosis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a typical prior art pressuremonitoring apparatus.

FIG. 2 is a greatly enlarged, side elevational, cross sectional view ofone of the stopcocks, or valves, used in the prior art apparatus of FIG.1.

FIG. 3 is a side elevational, cross sectional view of a typical priorart heparin lock.

FIG. 4 is a side elevational, cross sectional view of a typical priorart "T" connector.

FIG. 5 is a side elevational view, partly in cross section, of one formof the fluid sampling apparatus of the present invention for use inconjunction with prior art monitoring systems of the characterillustrated in FIG. 1.

FIG. 6 is a cross sectional view taken along lines 6--6 of FIG. 5showing the internal construction of one form of the fluid samplingassemblages of the apparatus of the invention.

FIG. 7 is a plan view taken along lines 7--7 of FIG. 5.

FIG. 8 is a cross sectional view of an alternate form of fluid samplingassemblage of the present invention.

FIG. 9 is a side elevational view partly in cross section of analternate form of the fluid sampling apparatus of the present invention.

FIG. 10 is a side elevational view partly in cross section of anotherform of the fluid sampling apparatus of the present invention.

FIG. 11 is a side elevational view partly in cross section of stillanother form of the fluid sampling apparatus of the present invention.

FIG. 12 is a side elevational view partly in cross section of a furtheralternate form of the fluid sampling apparatus of the present invention.

FIG. 13 is a side elevational view partly in cross section of yetanother form of the fluid sampling apparatus of the present invention.

FIG. 14 is a view taken along lines 14--14 of FIG. 13.

DESCRIPTION OF THE INVENTION

Before considering the apparatus of the present invention, a briefreview of the prior art methods and apparatus for arterial and venousblood sampling is believed necessary for a complete appreciation of thenovelty and scope of the present invention. Referring to the drawingsand particularly to FIGS. 1 and 2, one form of prior art sampling systemis thereshown. Such systems generally comprise an intravenous (IV)administration set 10, a continuous flush device (CFD) 12, severallengths of IV or pressure tubing 14, two or more three port stopcocks16, a pressure transducer-dome set 18, and either an arterial or venouscatheter (one to five lumens). Generally the entire monitoring system isfilled with heparinized solution to prevent blood coagulation (tomaintain patency in the line) and to provide the medium for transmissionof the patient's cardiac pressure to the monitoring equipment.

Typically the IV administration set 10 includes a spike 20, a rollerclamp 22 and suitable tube connectors 24. In FIG. 1, the stopcocks 16are shown in the all closed position and the sideports are shown sealedagainst atmosphere by port protectors, or dead end caps, 26.

Turning to FIG. 2, the prior art stopcock 16 comprises a body 28 havinga central chamber, or core, 30 in communication with inlet, outlet andsideport fluid passages 32, 34 and 36 respectively. A flow controlmember 38 having a "T" shaped fluid passageway 40 is rotatably carriedwithin central chamber 30 and functions to selectively control the flowof fluid through the various fluid passageways of the stopcock.

When the prior art "stopcock sampling method" is used, the sideport 37of the three port stopcock provides access to the monitoring line forblood sampling. This "stopcock" technique commonly comprises thefollowing steps:

(1) turning the stopcock control member 38 in a manner to close off sideport passageway 36 (FIG. 2);

(2) removing the protector cap 26;

(3) aseptically wiping the sideport surfaces with a sterile solutionsuch as alcohol or iodine solution;

(4) substituting a sterile syringe (not shown) for the protector cap;

(5) rotating the stopcock control member, including the handle, to afirst position where it blocks CFD flow via passageway 32 while openingpassageway 34 to the patient and passageway 36 to the syringe;

(6) aspirating all the heparin or flush solution (plus some amount ofblood) from the line leading to the patient and causing the line to fillcompletely with the patient's blood;

(7) turning the stopcock control member to a second position, midwaybetween passageway 32 and passageway 36, which blocks flow through allpassageways;

(8) removing and discarding the syringe with the extracted heparinsolution and some waste blood;

(9) attaching a new sterile syringe to the stopcock sideport 37 andreturning the stopcock control member to its first position;

(10) aspirating the blood specimen into the syringe and then turning thestopcock control member to close fluid flow to the syringe viapassageway 36 while reopening the heparin flow to the patient viapassageways 32 and 34;

(11) removing the syringe and forwarding the blood sample for laboratoryanalysis;

(12) activating the CFD to purge the remaining blood in theintra-arterial/venous line back into the patient;

(13) turning the stopcock control member so as to block fluid flow inthe patient's direction via passageway 32 while opening the fluid flowfrom heparin source to the stopcock sideport;

(14) again activating the CFD to purge the residue blood from stopcocksideport; and

(15) turning the stopcock control member one last time to continue fluidflow communication between heparin source and patient via passageways 32and 34 while blocking fluid flow to the sideport passageway 36 andfinally attaching the port protector 26 to the sideport.

The "stopcock" method as described in the preceding paragraphs presentsseveral serious problems. For example, the repeated invasion of thenormally atmospherically sealed arterial/venous line using stopcocks isa major source for nosocomial infection both in the actual bloodsampling steps as well as in the steps involving the handling orreplacement of port protectors. Several medical researchers haveidentified these procedures as primary sources for contamination. Seefor example, Weinstein et al, Pressure Monitoring Devices: OverlookedSource of Nosocomial Infection, JAMA 1976, 236:936; Walrath J. M., etal, Stopcock: Bacterial Contamination in Invasive Monitoring Systems,Heart Lung 1979, 8:100; Spaccavento, L.T., Hawley H. B., InfectionsAssociated with Intraarterial Lines, Heart Lung 1982, 11:228; Center forDisease Control, National Nosocomial Infections Study Report, AnnualSummary, 1979, p. 31e); McArthur, B. J. et al, Stopcock Contamination inan ICU, AJN 1975 75:96, and Shinosaki et al, Bacterial Contamination ofArterial Lines, Jan. 14, 1983, vol. 249.

Another serious problem inherent in the "stopcock" method involves theunavoidable entry of air into the sample via side port passageway 36during the sampling steps thereby causing potential error in the sampleanalysis and in pressure measurements. See, for example, the articles byMueller et al, Bubbles in Samples for Blood Gas Determinations. APossible Source of Error, 1979 Am J. Clin Pathol vol 65, pg. 242-249;Agroyanmis, et al, Blood Gas Analysis on Air Bubbles in Syringe andDelay in Estimation, Brit Med J. March 1982, vol 284; and Ishikawa etal, The Effects of Air Bubbles and Time Delay on Blood Gas Analysis, AnnAllergy 1974, vol 33 which discuss this problem.

Additionally, use of the "stopcock" procedure requires that theclinician unavoidably discard a small amount of blood in order toacquire nondiluted blood samples. Where absolute minimal samples must bewithdrawn, as is the case with neonates, blood waste is extremelycritical and often unacceptable since the waste blood cannot bereplaced.

Finally, error in stopcock manipulation or failure to properly cap openports can also lead to gross blood loss and catastrophic results.

Because of the serious problem inherent in the "stopcock" samplingmethod, various modifications of the above procedure have beensuggested. For example, two stopcocks inline have been suggested toprevent opening the system to air. However, due to the fact thatstopcocks inherently embody large dead space volumes, as for example inone leg of the fluid flow control member, this procedure unavoidablyresults in unacceptable dilution of the fluid sample and results inserious errors in analysis determination. Many papers have been printedon the topic of blood analysis problems associated with dilutionincluding: Dennis, R. C. et al, Effects of Sample Dilutions on ArterialBlood Gas Determinations, Clin Care Nurs 1985, vol 13, no. 12;Hutchinson A. S. et al, Too Much Heparin; Possible Source of Error inBlood Gas Analysis, Brit Med J 1983, vol 287, no 15; and Drake M. D. etal, The Effect of Heparin Dilution on Arterial Blood Gas Analysis, TheWest J Med 1984, vol 140, no 5.

In summary, dilution of the blood sample can effect the clinicaldetermination of PH, carbon dioxide pressure, base excess, oxygenpressure and actual bicarbonate concentration as well as other testparameters. Because dilution can result in substantial clinical errorwith higher risk existing when small blood volumes are sampled usingcurrent techniques, some medical experts recommend larger volumes ofwaste blood be discarded prior to blood sampling even when only the deadspaces are filled with heparin. However, in certain situations (neonatalblood sampling) where the absolute minimal amount of blood can beremoved from the patient, it is impossible to acquire a sufficientlydilution free sample using current techniques and components.

Prior art sampling techniques other than the stopcock sampling techniquehave occasionally been used. These techniques generally include the use,in conjunction with the stopcock, of either a heparin lock or a "T"connector.

FIG. 3 illustrates the configuration of a heparin lock and FIG. 4 showsthe configuration of a typical "T" connector. The heparin lock,generally designated in FIG. 3 by the numeral 46, includes a body 48having an upper portion 50, a lower tapered portion 52 and a passageway54 extending therethrough. An internally threaded female adapter iscarried by portion 52 for threadable interconnection with the sideport37 of stopcock 16. Closing the upper end of passageway 54 is a cap ordiaphragm 56 usually constructed of natural or synthetic rubber.

Turning to FIG. 4, the prior art "T" connector comprises a "T" shapedbody 60 having a first passageway 62 and a perpendicularly extendingsecond passageway 64. The upper end of passageway 62 is closed by arubber cap or diaphragm 66, while passageway 64 is adapted tocommunicate with a length of conduit or tubing 68 which can be removablyinterconnected with the connector body.

When the prior art "heparin lock" sampling method is practiced,connection of the device is made with the idle port of the stopcock.Next, the clinician punctures the diaphragm or injection site with theneedle of a hypodermic needle. The procedure described in the precedingparagraphs is then followed using the syringe/hypodermic needlecombination in place of the individual syringe used to aspirate fluidsin the "stopcock" method.

When the prior art "T-connector" sampling method is practiced, the"T-connector" is inserted between the arterial or venous catheter andthe male connector of the distal pressure tube, shown at "A" in FIG. 1.The clinician uses a similar procedure as with the "heparin lock".

As in the case of the stopcock method, the "heparin lock" and"T-connector" methods present serious difficulties. After initialconnection of either the "heparin lock" or "T-connector" to thestopcock, the need to directly access the sideport as an open system,that is a system open to atmosphere, is eliminated. This constitutes theprimary advantage of these methods over the "stopcock" method and tendsto reduce the potential for contamination. However, significant problemsstill remain. For example, the basic design of both the "heparin lock"and the "T-connector" prevents effective purging from the system ofeither heparin solution prior to sampling or residue blood aftersampling. In point of fact, utilization of "heparin lock" in thesideport of the stopcock substantially increases the "dead space" volumeof the system making it virtually impossible to either purge or access apure blood sample. In other words, these latter methods while solvingone problem create several others. Further, and of substantialimportance is, the fact that the designs of both the "heparin lock" and"T-connectors" provide absolutely no structure which will efficientlyprotect clinicians from accidental skin puncture by a hypodermic needle.

Turning now to a consideration of the method and apparatus of thepresent invention, it will be appreciated from the discussion whichfollows that the several previously identified drawbacks of the priorart are uniquely overcome. Referring to FIGS. 5, 6 and 7 of thedrawings, the apparatus of the invention comprises a length of flexibletubing 70 having connector means in the form of a threaded connector 72on one of its ends. The other end of tubing 70 is interconnected with afirst of two identical fluid sampling means of the apparatus of theinvention. A second length of flexible tubing 74 is disposedintermediate the first sampling means, or sampling device, 76 and asecond sampling device 78. A third length of flexible tubing 80 isconnected at one end to second sampling device 78 and has at its freeend connector means in the form of a threaded connector 82.

Referring to FIG. 1, which shows a typical prior art pressure monitoringsystem, the apparatus of the present invention would normally beinterconnected between points A and B, with threaded connectors 72 and82 being interconnectable with mating connectors or with valving meanssuch as three port stopcocks of the character shown in FIG. 2. When theapparatus is disposed intermediate two stopcocks, one of the stopcocksis in fluid communication with an intravenous or intraarterial catheterinvasively connected to the patient and the other is in communicationwith an IV source. For most applications, one of the stopcocks can beeliminated and one of the fluid sampling devices can be interconnecteddirectly with the catheter.

As best seen in FIGS. 5 and 6, each of the fluid sampling devicescomprises a plastic housing, or body, 84 having upper and lower chambers86 and 88 and a diaphragm or septum 90 sealably carried within upperchamber 86 to seal the lower chamber relative to atmosphere. Lowerchambers 88 are provided with smoothly curved bottom and side walls andlongitudinally spaced fluid inlet and outlet ports 92 and 94respectively which communicate with the flexible tubing whichinterconnects the two sampling devices and which interconnects thesampling devices with the 3-way (three-way) stopcocks. Diaphragms 90,which are preferably constructed of natural or synthetic rubber orsylastics, are secured in place within chambers 86 by inturned flanges96 formed circumferentially about the tops of housings 84. Thediaphragms are provided in the form of solid cylinders and are seated inclose proximity with the inlet and outlet ports 92 and 94 so as tominimize dead fluid volume in transverse or angular lumens. Whenpunctured with a sharp instrument, such as the needle on a hypodermicsyringe, the diaphragms function as gaskets and are self-sealing aboutthe instrument thereby preventing fluid leakage and air entry to thesystem while at the same time providing a sterile barrier to atmosphere(see the phantom lines in FIGS. 5 and 6).

Housings 84 are preferably constructed from a rigid, transparent plasticpolycarbonate material, although other rigid, substantially transparentor translucent plastic materials can be used. These materials provideimportant clear visibility into the lower chamber for sample examinationor air bubble detection. The inlet and outlet ports of the body aredesigned such that the outside circumference of the flexible tubing canconveniently be bonded to the ports using commercially availablesolvents. The entry and exit paths into the lower fluid chamber smoothlymate tangently to the inside diameter of the flexible tube to providenonturbulent fluid flow and to significantly minimize dead space volume.

Referring once again to FIGS. 3 and 4 which are illustrations of theprior art "heparin lock" and "T-connector" designs. At first blush,these designs appear to be somewhat similar to that of the fluidsampling device of the present invention. However, upon closerexamination, it becomes clear that these designs are, in fact, quitedifferent since both the "heparin lock" and "T-connector" lumen designsprovide no efficient means of purging the transverse lumens of residuefluids, thereby permitting entrapment of significant volumes of stagnantfluid. Further, because of the nature of these prior art designs, it isvirtually impossible to effectively purge the devices of residualfluids. Accordingly, since the diaphragm of the devices is, ofnecessity, used as the fluid sampling port, the blood specimens whichare obtained are invariably diluted with residual fluids which have notbeen effectively purged from the system.

Turning again to FIGS. 5, 6 and 7, the body, or housing, 84 of the fluidsampling devices include gripping means for securely and positivelygripping the fluid sampling device between the thumb and forefinger andshield means disposed between the gripping means and the upper chamberof the body for protecting the thumb and finger against accidentalpuncture by the needle of the hypodermic syringe during penetration ofthe sealing means in the manner shown in FIGS. 5 and 6. In the form ofthe invention illustrated in the drawings, the gripping means isprovided in the form of a first generally planar member 100 which isdisposed in a longitudinally downwardly extending plane from the lowerportion, or lower chamber, 88 of the body (See FIG. 6). Planar member100 is cut away in the area of lower chamber 88 at 101 to provideunobstructed visibility to the transparent lower chamber. As best seenby referring to FIGS. 6 and 7, the shield means of the present form ofthe invention comprises a second generally planar member 102 which isdisposed in a plane extending generally perpendicular to the plane ofthe first planar member 100. As best seen in FIG. 6, this shield, orsecond planar member 102, is disposed intermediate the gripping member100 and the upper portion of the body which houses the septum 86. Withthis arrangement, when the user grips the fluid sampling device as, forexample, between the thumb and forefinger, these fingers will beimplaced safely beneath the shield member 102 as indicated in thephantom lines in FIG. 6. Accordingly, should the clinician accidentallymisdirect the needle of the hypodermic syringe, it will harmlesslyimpact the shield member 102 and will not puncture the fingers used togrip the device. This highly important feature of the invention guardsagainst serious or even fatal contamination of the clinician as a resultof a puncture wound by a contaminated hypodermic needle. See, forexample, the articles by McCormick et al, Epidemiology of Needle StickInjuries in Hospital Personnel, Am J. Med, April 1981, Volume 70, page928; Hamory, B., Under-Reporting of Needle Stick Injuries in aUniversity Hospital, Am J Inf Cont., October 1983, Volume 11, No. 5; NewEng J Med, H.I.V. (Aids) Infection with Seroconversior after aSuperficial Needle Stick Injury to the Finger, Aug. 28, 1986, page 582;Center for Disease Control (C.D.C.), Recommendations for PreventingTransmission of Infection with Human T-Lymphotropic Virus Type 3(HTLV-3/Lymphadenopathy Associated Virus (LAV) in the Workplace, [HumanImmunodeficiency Virus (H.I.V. - Aids)], Morb and Mort Weekly Rept, Nov.15, 1985, Volume 34, No. 45; Center for Disease Control (C.D.C.),Guidelines for Handwashing and Environmental Control, C.D.C., 1985.

Turning to FIG. 8, an alternate form of the fluid sampling device of thepresent invention is there illustrated. This device is similar inconstruction to the fluid sampling device shown in FIG. 5 and includes ahousing or body 110 provided with upper and lower chambers 112 and 114respectively. Lower chamber 114 is provided with fluid inlet and outletports 116 and 118. These fluid inlet and outlet ports can beinterconnected with other components of the system in the same manner asdiscussed in connection with the embodiment of the invention shown inFIG. 5.

In the form of the invention shown in FIG. 8, the diaphragm, or septum,is of a somewhat different configuration, being generally frustoconicalin cross section. Additionally, in this instance, the septum, ordiaphragm, 120 is sealably carried within upper chamber 22 by means of aclosure means, or cap, 122 which fits closely about the walls of thebody portion which define upper chamber 112. Cap 122 is provided with acentral aperture 124 which permits access to the septum 120 by theneedle of a hypodermic syringe. The side walls of aperture 124 areinwardly tapering so as to guide the hypodermic needle toward thediaphragm, or septum, 120. For certain applications, and to aid inclinician training and differentiation, the cap 122 of one of the fluidsampling devices is provided in a first color while the cap of a secondof the fluid sampling devices is provided in a second, different color.

The body of the fluid sampling device shown in FIG. 8 is preferablyconstructed of a transparent or translucent plastic, such aspolycarbonate. The cap 22 is preferably constructed of a flexibleplastic material so that the skirt portion 122a thereof can be deformedslightly so as to snap over a circumferentially extending locking bead126 formed on the outer surfaces of the walls which define the upperchamber 112.

The fluid sampling device of FIG. 8 is also provided with gripping meansand shield means of generally the same configuration previouslydiscussed in connection with the first embodiment of the invention.

When it is desired to use the apparatus of the present invention inconnection with a prior art monitoring system, the apparatus of FIG. 5is interconnected with the monitoring system between points "A" and "B"(FIG. 1). The first connector means, as, for example, connector 82, isinterconnected with a suitable valve such as a three-way stopcock of thecharacter shown in FIG. 1 and designated by the letter "S". As indicatedin FIG. 1, this stopcock is in turn interconnected with the remotesource of fluid such as heparinized IV. The second connector means ofthe apparatus, as, for example, connector 72, is preferablyinterconnected with the fluid conduit leading to the catheter which isconnected to the patient. For certain applications, however, the secondconnector 72 can be interconnected with a valve such as a stopcock whichis in turn in communication with the catheter.

After the apparatus of the invention has been interconnected with aprior art system of the character shown in FIG. 1, the first step of thepreferred method of the invention is to turn the stopcock memberprecisely midway between the stopcock sideport and either endport(effectively closing all ports) of the stopcock "S" to block fluid flowfrom the fluid supply means towards the lower, or first, chamber 88 ofthe first fluid sampling device. This, of course, discontinues the flowof IV solution to the patient. It is to be noted that it is recommendedthat the stopcock port protector or dead-ender not be removed from thestopcock. Next, the diaphragm surface of the first or proximal fluidsampling device is carefully cleaned with an aseptic solution. Thisdone, chamber 88 is accessed with the needle of a first syringe in themanner shown in the phantom lines in FIG. 5. Preferably the needle isinserted to a depth of about one centimeter. Using the syringe, all ofthe fluid contained within the system between the stopcock "S" and thepatient is then removed and withdrawn into the syringe. In other words,all fluids contained within the fluid conduits leading to the catheter,namely fluid conduits 70 and 74 and all fluids within the fluid chambers88 of the first and second sampling devices are withdrawn into thesyringe. Continued withdrawal of fluid by the syringe will result in therefilling of the system with fresh, undiluted blood drawn from thepatient. Accordingly, at the completion of this step, the entire systembetween the syringe and the catheter is filled with the undiluted bloodwithdrawn from the patient. The hypodermic needle is then removed fromthe proximal fluid sampling device and the first syringe/needle unit,including the waste heparinized IV fluid, is discarded.

The next step in the process of the invention is to carefully clean thediaphragm of the second, or distal, fluid sampling device using anaseptic solution and then to access chamber 88 of the second fluidsampling device, using a second syringe. A predetermined, precise volumeof the undiluted blood contained within chamber 88 of the secondsampling device can then be removed and the syringe capped forforwarding to the laboratory for testing. The final step in the methodof the invention is to once again open valve, or stopcock, "S" to permitfluid flow from the fluid supply means toward the patient. Once thisvalve is opened, the blood remaining within the system, that is, theblood which had not been withdrawn in the taking of the sample, willflow back into the patient via the fluid conduits and the catheterconnected to the patient. In this way no blood is wasted and no dilutedblood is contained with the sample taken.

The previously identified method of the invention can be modified whendifferent configurations or system components are used in the fluidsampling system. For example, one alternative configuration would be touse a single fluid sampling device distal to the catheter in-line with athree port stopcock or heparin lock proximate to the catheter to performa similar blood sampling technique. Another variation would include theuse of more than two fluid sampling devices in-line wherein anycombination of fluid sampling device can be used in a similar samplingmethod.

Turning to FIGS. 9, 10 and 11, three alternate forms of the apparatus ofthe present invention are there illustrated. The apparatus shown inthese figures is similar in construction to the apparatus shown in FIG.5 and like numbers are used in FIGS. 9, 10 and 11 to identify likecomponents. The form of the apparatus shown in these drawings includes afirst, or proximal, access device P which is of identical constructionto the sampling devices 76 and 78 comprising a housing or body 84provided with upper and lower chambers 86 and 88 respectively. Lowerchamber 88 is provided with fluid inlet and outlet ports 92 and 94.These fluid inlet and outlet ports can be interconnected with othercomponents of the system in the same manner as discussed in connectionwith the embodiment of the invention shown in FIG. 5. More particularly,the apparatus of these alternate forms of the invention each comprises alength of flexible tubing 70 having connector means in the form of athreaded connector 72 on one of its ends. Connector 72 enablesinterconnection of the apparatus with a catheter adapted to be insertedinto a vein or artery of the patient. The other end of tubing 70 isinterconnected with the proximal access device P. A second length offlexible tubing or conduit 74 is disposed intermediate the proximalaccess device, or sampling means, and a distal access device.

Each of the proximal access devices includes a sealing means shown as adiaphragm or septum 90. The sealing means is penetrable by a needle of asyringe to gain access to the lower chamber. Lower chambers 88 areprovided with smoothly curved bottom and side walls and thelongitudinally spaced fluid inlet and outlet ports 92 and 94 communicatewith the interior of flexible tubing 70 and 74. The proximal accessdevice is specifically designed to provide smooth, laminar fluid flowtherethrough and includes no dead spaces wherein fluid can be trapped.

As is the case with previously described sampling devices 76 and 78,housing 84 of the proximal access, or sampling, device P includesgripping means 100 for securely and positively gripping the fluidsampling device between the thumb and forefinger and shield means 102disposed between the gripping means and the upper chamber of the bodyfor protecting the thumb and finger against accidental puncture by theneedle of the hypodermic syringe during penetration of the sealing meansin the manner shown in FIGS. 5 and 6. The form of the gripping means andshield means of the apparatus shown in FIGS. 9, 10 and 11 is identicalto that previously described herein.

Turning now particularly to FIG. 9, the distal accessing, or sampling,device 140 is provided in the form of a "Y" site. Access device 140comprises an elongated chamber 142 which is coaxially aligned with, andin communication at its inlet 144 with, the fluid passageway of tubing,or conduit 74. Provided at the opposite end of chamber 142 is sealingmeans, shown here as a septum 146. Septum 146 seals chamber 142 withrespect to atmosphere, but is penetrable by the hypodermic needle of asyringe so that access may be had to chamber 142. Extending angularlywith respect to chamber 142, is a second elongated chamber 148 having anoutlet 150 which is connected to a third length of flexible tubing 152.Tubing 152 can be connected at is opposite end with other componentssuch as an IV set (not shown) and can be closed by a suitable valve orclamp of a character well-known to those skilled in the art.

Turning to FIG. 10, the distal access device 154 in this embodiment ofthe invention is provided in the form of a stopcock having the generalconstruction illustrated in FIG. 2 of the drawings. Device 154 includesa body 155 having central chamber 156 within which a flow control member158 is rotatably carried. Central chamber 156 is in communication withinlet, outlet and sideport fluid passageways 160, 162 and 164respectively. As indicated in FIG. 2, member 158 has a "T" shaped fluidpassageway which enables the control of fluid flow through the variousfluid passageways of the device. Sideport fluid passageway 164 includesa connector which is adapted to be accessed by interconnection therewithof a syringe to gain access to chamber 156. Passageway 164 can also beaccessed by interconnection therewith of a heparin lock having a septumpenetrable by the needle of a hypodermic syringe. Outlet passageway 162can be interconnected with external components, such as IV sets, bymeans of a length of tubing or conduit 168.

Referring to FIG. 11, the distal access device 170 of this embodiment isprovided in the form of a heparin lock of the general configurationshown in FIG. 3. Heparin lock, or access device, 170 includes a body 172having a portion 174, a tapered portion 176 and a central chamber 178extending therethrough. An internally threaded female adapter is carriedby portion 176 for threadable interconnection with a suitable adapterwhich permits interconnection of the device with conduit 74 (see FIG.3). Closing the distal end of chamber 178 is a cap or diaphragm 182preferably constructed of natural or synthetic rubber, which ispenetrable by the needle of a syringe to gain access to chamber 178.

After the apparatus of the invention as shown in FIGS. 9 and 10 has beeninterconnected via tube 70 with a catheter which is interconnectedinvasively with the patient, the first step in using the apparatus is toclamp off tube 152 (FIG. 9), or to rotate the control member 158 of thestopcock to block fluid flow from the IV set or other fluid supply meanstowards the chambers 142 and 156 of the distal fluid sampling or accessdevices. Next, the septum surface of the distal fluid sampling device(FIG. 9), or the sideport surfaces (FIG. 10), is carefully cleaned withan aseptic solution. This done, chamber 142 (FIG. 9) or chamber 156(FIG. 10) is accessed with a first syringe. Using the syringe, all ofthe fluid contained within the system between the distal access deviceand the patient is then removed and withdrawn into the syringe. In otherwords, all fluids contained within the fluid conduits leading to thecatheter, namely fluid conduits 70 and 74 and all fluids within thefluid chamber 88 of the proximal sampling or access device P iswithdrawn into the syringe. Continued withdrawal of fluid by the syringewill result in the refilling of the system with fresh, undiluted blooddrawn from the patient. Accordingly, at the completion of this step, theentire system between the syringe and the catheter is filled with theundiluted blood withdrawn from the patient. The hypodermic needle isthen removed from the distal access device and the total unit, includingthe waste heparin, is discarded.

The next step in the process of the invention is to carefully clean thediaphragm of the proximal fluid sampling device using an asepticsolution and then to access chamber 88 of the proximal access device,using a second syringe. A predetermined volume of the undiluted bloodcontained within chamber 88 of the proximal access device P can then beremoved and the syringe and its contents forwarded to the laboratory fortesting. The final step in the method of the invention is to once againopen the clamp, valve, or stopcock, of the particular apparatus topermit fluid flow from the fluid supply means toward the patient.

In using the apparatus of the invention shown in FIG. 11, connector 72is interconnected with the catheter and the septum 182 is carefullycleaned with an antiseptic solution. This done, chamber 178 is accessedwith the needle of a first syringe. Using the syringe, all of the fluidcontained within the system between the distal access device and thepatient is then removed and withdrawn into the syringe. In other words,all fluids contained within the fluid conduits leading to the catheter,namely fluid conduits 70 and 74 and all fluids within the fluid chamber88 of the proximal access device P is withdrawn into the syringe.Continued withdrawal of fluid by the syringe will result in therefilling of the system with fresh, undiluted blood drawn from thepatient. Accordingly, at the completion of this step, the entire systembetween the syringe and the catheter is filled with the undiluted bloodwithdrawn from the patient. The hypodermic needle is then removed fromthe distal access device and the total unit, including the wasteheparin, is discarded.

The next step in the process of the invention is to carefully clean thediaphragm of the proximal fluid sampling device using an asepticsolution and then to access chamber 88 the proximal access device, usinga second syringe. A predetermined volume of the undiluted bloodcontained within chamber 88 of the proximal access device P can then beremoved and the syringe and its contents forwarded to the laboratory fortesting.

Turning to FIGS. 12, 13 and 14, two further alternate forms of theapparatus of the present invention are there illustrated. The apparatusshown in these Figures is similar in construction to the apparatus shownin FIGS. 9 and 10 and like numbers are used in FIGS. 12, 13 and 14 toidentify like components. More particularly, the apparatus of thesealternate forms of the invention each comprises a length of flexibletubing 70 having connector means in the form of a threaded connector 72on one of its ends. Connector 72 enables interconnection of theapparatus with a catheter adapted to be inserted into a vein or arteryof the patient. The other end of tubing 70 is interconnected with theproximal access device, the construction of which will presently bedescribed. A second length of flexible tubing or conduit 74 is disposedintermediate the proximal access device, or sampling means, and a distalaccess device, shown in the drawings as a stopcock which is of similarconstruction to stopcock 155 shown in FIG. 10.

Referring to FIG. 12, the proximal access device 188 thereshown includesa sealing means shown as a diaphragm or septum 190. The sealing means iscontained within hollow body 191 and is penetrable by a needle of asyringe to gain access to the lower chamber 192 of the hollow body.Lower chamber 192 is provided with smoothly curved bottom and side walls194 an 196. Longitudinally spaced fluid inlet and outlet passageways 198and 200, respectively, communicate with the interior of flexible tubing70 and 74. As in the earlier described embodiments of the invention, theproximal access device is specifically designed to provide smooth,laminar fluid flow therethrough and includes no dead spaces whereinfluid can be trapped. However, unlike the previously described proximalaccess devices P, the side walls 196 of the device shown in FIG. 12extend at an angle with respect to the coaxially aligned fluid inlet andfluid outlet passageways. With this construction, the needle N isinserted into the angularly disposed septum 190 at an angle with respectto the longitudinal axis of tubing 70 and 74. Additionally, the accessdevice 188 is provided with a novel shield means, provided here in theform of a circular, disc-like member 201, which is connected proximatethe top of the device and functions to prevent accidental puncture ofthe fingers of the technician during insertion of the needle N into theseptum.

The distal access device 204 in the embodiment of the inventionillustrated in FIG. 12 is provided in the form of a stopcock. Device 204includes a body 206 having central chamber 208 within which a flowcontrol member 210 is rotatably carried. Central chamber 208 is incommunication with inlet, outlet and sideport fluid passageways 212,214, 152 and 216 respectively. Member 210 has a "T"-shaped fluidpassageway which enables the control of fluid flow through the variousfluid passageways of the device. Sideport fluid passageway 216 can beaccessed in various ways. The port is shown in the drawings beingcovered by a cap 217 which is penetrable by the needle of a syringe.Similarly, outlet passageway 212 can be interconnected with externalcomponents, such as IV sets, by means of a length of tubing or conduit218.

Referring now to FIG. 13, the proximal access device 220 of thisembodiment of the invention includes a hollow body 222 within which ismounted a sealing means or septum 224. The sealing means is penetrableby a needle N of a syringe to gain access to the lower chamber 226.Chamber 226 is provided with smoothly curved bottom and side walls 228and 230. In this latter form of the invention, the fluid inletpassageway 232 and fluid outlet passageway 234 are uniquely arranged sothat they extend at an angle with respect to each other in the mannershown in FIG. 13. Outlet passageway 234 communicates with tubing 74 andis coaxially aligned with outlet port 214 of the distal access device206, which is of identical construction to that shown in FIG. 12 andpreviously described herein. Inlet passageway 232 communicates withtubing 70 which extends at an angle with respect to tubing 74.

In certain applications, it is desirable to provide means for positivelypreventing retroflow through tubing 74. In such instances means, shownhere as a duckbill-type check valve 235, is inserted within passageway234 in the manner shown in FIG. 13. It is to be understood that varioustypes of check valve designs could be used for this application.

As in the earlier described embodiments of the invention, the proximalaccess device 220 is specifically designed to provide smooth, laminarfluid flow therethrough and includes no dead spaces wherein fluid can betrapped. Because of the unique angular relationship of the body 222 withrespect to outlet passageway 234, the needle N is inserted in an angularfashion in the manner illustrated in FIG. 13. As best seen by referringto FIG. 14, shield means in the form of a disc-like member 237, which issimilar to shield member 201, is integrally formed with body 222 toprotect the thumb and finger of the technician against accidentalpuncture by the needle N of the hypodermic syringe during penetration ofthe sealing means 20a.

After the apparatus of the invention as shown in FIGS. 12 and 13 hasbeen interconnected via tube 70 with a catheter which is interconnectedinvasively with the patient, the first step in using the apparatus is torotate the control member 210 of the stopcock to block fluid flow fromthe IV set or other fluid supply means towards the chambers of thedistal fluid sampling or access devices. Next, the side port cap 217 iscarefully cleaned with an aseptic solution. This done, chamber 208 isaccessed with a first syringe. Using the syringe, all of the fluidcontained within the system between the distal access device and thepatient is then removed and withdrawn into the syringe. In other words,all fluids contained within the fluid conduits leading to the catheter,namely fluid conduits 70 and 74 and all fluids within the fluid chambersof the proximal sampling or access devices is withdrawn into thesyringe. Continued withdrawal of the fluid by the syringe will result inthe refilling of the system with fresh, undiluted blood drawn from thepatient. Accordingly, at the completion of this step, the entire systembetween the syringe and the catheter is filled with the undiluted bloodwithdrawn from the patient. The hypodermic needle is then removed fromthe distal access device and the total unit, including any wasteheparin, is discarded.

The next step in the process of the invention is to carefully clean thediaphragm of the proximal fluid sampling device using an asepticsolution and then to access chamber 192 (FIG. 12) or chamber 226 (FIG.13) of the proximal access device, using a second syringe. Apredetermined volume of the undiluted blood contained within the chamberof the proximal access device can then be removed and the syringe andits contents forwarded to the laboratory for testing. Any excessuncontaminated blood or other fluids can then be readministered to thepatient through the proximal fluid accessing device 188 or 220 to avoidexcessive fluid loss. The final step in the method of the invention isto once again open the stopcock to permit fluid flow from the fluidsupply means toward the patient.

Alternatively, due to the laminar fluid flow design without dead spaces,an undiluted volume of blood or other solution can be effectivelyadministered without fluid becoming trapped in the device. The fluidshould be administered through the proximal device 188 or 220,preferably with the stopcock or fluid source in the closed position,however, this is not necessary to achieve the undiluted administration.When a check valve, such a check valve 235 is used in the system thestopcock need not be closed.

Having now described the invention in detail in accordance with therequirements of the patent statutes, those skilled in this art will haveno difficulty in making changes and modifications in the individualparts or their relative assembly in order to meet specific requirementsor conditions. Such changes and modifications may be made withoutdeparting from the scope and spirit of the invention, as set forth inthe following claims.

I claim:
 1. An apparatus for use in conjunction with a system which isclosed to the atmosphere and interconnected invasively to a patient forobtaining a blood sample from the patient and for administering bloodand other fluids to the patient, said system being characterized byhaving a catheter adapted to be inserted into a vein or artery of thepatient, said apparatus comprising proximal and distal, spaced apartaccess devices operably interconnected by a conduit having a fluidpassageway, each of said access devices being independently accessibleto withdraw fluid from within the system, said proximal access devicecomprising a body having bottom and side walls defining an upper andlower chamber, said lower chamber being in communication with first andsecond coaxially aligned fluid passageways, said side wall extending atan acute angle with respect to said fluid passageways and sealing meanscarried by said upper chamber for sealing said lower chamber relative toatmosphere, said sealing means being penetratable by a needle of asyringe to gain access to said lower chamber, said proximal accessdevice permitting smooth, laminar fluid flow therethrough and includingfirst connector means for interconnecting said first fluid passageway ofsaid body of said proximal access device with the catheter of the systemand further including means for interconnecting said second fluidpassageway of said body of said proximal device with said conduit, saiddistal access device comprising a chamber in communication with saidfluid passageway of said conduit and means for accessing said chamberwhereby said chamber of said distal access device can be accessed towithdraw from the apparatus all fluid contained between the catheter andsaid chamber of said distal access device and to withdraw blood from thepatient in a quantity sufficient to draw blood past said first chamberof said proximal access device so that said lower chamber of saidproximal access device can be accessed to withdraw and return therefromundiluted blood contained therewithin, in a manner such that when saidsample is accessed from said proximal access device, the system is notopened to atmosphere.
 2. A fluid sampling and administration apparatusdevice as defined in claim 1 further including shield means integrallyformed with said body for protecting the thumb and finger againstaccidental puncture by the needle of the hypodermic syringe duringpenetration of said sealing means.
 3. A fluid sampling andadministration apparatus as defined in claim 2 in which said shieldmeans comprises a generally circular shaped thin disk.
 4. A fluidsampling and administration apparatus as defined in claim 3 in whichsaid distal access device is provided in the form of a stopcockincluding sealing means for sealing said chamber to atmosphere and aflow control member having a "T" shaped fluid passageway rotatablycarried within said chamber.
 5. A fluid sampling and administrationapparatus as defined in claim 3 further including means for preventingretroflow of fluid between said proximal access device and said distalaccess device.
 6. An apparatus for use in conjunction with a systemwhich is closed to the atmosphere and interconnected invasively to apatient for obtaining and returning a blood sample from the patient,said system being characterized by having a catheter adapted to beinserted into a vein or artery of the patient, said apparatus comprisingproximal and distal, spaced apart access devices operably interconnectedby a conduit having a fluid passageway, each of said access devicesbeing independently accessible to withdraw fluid from within the system,said proximal access device comprising a body having bottom and sidewalls defining an upper and lower chamber, said lower chamber being incommunication with first and second angularly disposed fluidpassageways, said side wall extending at an acute angle with respect toone of said first and second fluid passageways and sealing means carriedby said upper chamber for sealing said lower chamber relative toatmosphere, said sealing means being penetrable by a needle of a syringeto gain access to said lower chamber, said proximal access devicepermitting smooth, laminar fluid flow therethrough and including firstconnector means for interconnecting said first fluid passageway of saidbody of said proximal access device with the catheter of the system andfurther including means for interconnecting said second fluid passagewayof said body of said proximal device with said conduit, said distalaccess device comprising a chamber in communication with said fluidpassageway of said conduit and means for accessing said chamber wherebysaid chamber of said distal access device can by accessed to withdrawfrom the apparatus all fluid contained between the catheter and saidchamber of said distal access device and to withdraw blood from thepatient in a quantity sufficient to draw blood past said lower chamberof said proximal access device so that said lower chamber of saidproximal access device can be accessed to withdraw therefrom undilutedblood contained therewithin, in a manner such that when said sample isaccessed from said proximal access device, the system is not opened toatmosphere.
 7. A fluid sampling and administration apparatus as definedin claim 6 in which said wall of said proximal access device extends atan acute angle with respect to said second fluid passageway.
 8. A fluidsampling and administration apparatus as defined in claim 7 furtherincluding shield means integrally formed with said body of said proximalaccess device for protecting the thumb and finger against accidentalpuncture by the needle of the hypodermic syringe during penetration ofsaid sealing means, said shield means comprising a thin annular shapeddisc.